Ecology is fast becoming a buzzword of the '90s. If you have an inquiring mind and welcome unusual and even challenging experiences -- are you, for example, willing to sample the local fare of the country you are visiting? -- then you are a likely candidate for that relatively new and growing breed of leisure traveler: the ecotourist.

The world's great wild areas -- its tropical rain forests, wind-blown deserts, Arctic ice flows and mountain preserves -- are the new and often rugged "in" destinations these days for travelers who want to see them while they remain relatively pristine. As importantly, these travelers hope to contribute -- in a variety of ways -- to saving the wilderness. Rescuing endangered wildlife also ranks high in their priorities.

A diverse array of ecological tours is available these days, from private tour operators as well as conservation groups and other nonprofit organizations. You can:

Camp in the Costa Rican highlands.

Help plant trees in a reforestation project in Nepal.

Go on a foot safari in Africa.

Clean litter from Andean mountain trails in Peru.

Hike and study rain forest ecology in the Amazon Jungle.

Visit remote villages in India rarely opened to outsiders.

Observe newborn harp seal pups on an ice pack in Canada.

Cruise the remote southeastern coastal islands of Alaska on a little 70-passenger ship.

Join scientists in counting, banding and weighing penguins in the southern Patagonia region of Argentina.

Explore the rain forest of the diminutive Caribbean island of Dominica.

But not every nature tour qualifies as ecologically sensitive, and you should be aware of the distinction. Some tour operators reportedly are calling their programs "ecotours" when they are not really based on good conservation ethics. "A lot of the puff that goes on in ecotourism comes from people trying to attach a popular word on top of anything," says Virginia Hadsell of the Center for Responsible Tourism in San Anselmo, Calif.

They are a curious lot, the authentic ecotourists, willing to spend their vacation money and time learning about our environment and the threats to it in not always comfortable surroundings. "They travel with a mission," says Elizabeth Boo, who prepared a study earlier this year on "Ecotourism -- the Potentials and the Pitfalls" for the World Wildlife Fund in Washington. "They want to see their trip as meaningful."

To whom does this kind of travel appeal? "Nature tourists are generally more accepting of conditions different from home than are other types of tourists," wrote Boo in her report. They do not expect "accommodations, food or nightlife that meet the standards of comfort or luxury held by other groups of tourists." Indeed, many of them believe that unusual customs and foods actually "enrich their vacation experience."

Ecotourism might roughly be defined as going on a nature trip, whether it's bird-watching, hiking a mountain trail or snorkeling off a reef in Belize. But there is more to it than that. A key component for leaders in the ecotourism field is that nature or wildlife tours should be organized in a way that fosters preservation of wild areas and wildlife. Many conservationists have come to realize that tourism can have a beneficial impact on wild areas as well as a negative one, says Boo.

An excellent example are the annual winter tours to see the little fluffy white harp seal pups who are born in March on the floating ice fields just west of the Magdalen Islands in Canada's Gulf of St. Lawrence. In years past, the baby seals were slaughtered for their unusual fur by local hunters. The International Fund for Animal Welfare pushed for a ban, which the Canadian government adopted in 1987. Since then, the fund has sponsored a series of five- to eight-day seal-watching tours. Income from tourism has tripled what the islanders made from the annual hunt, says Richard Moore, the fund's executive director.

Wildland Journeys of Seattle sets aside part of the proceeds from all its nature tours to develop projects in the host country, according to Kurt Kutay, the firm's founder and a leader in the ecotourism movement. In the past, the firm has helped restore a Buddhist prayer wheel in the little Himalayan state of Ladakh, and once a year it organizes a reforestation project in Nepal as a three-day extension of a guided mountain trek.

The World Wildlife Fund, which sponsors numerous wildlife-viewing trips, has worked to establish guidelines for the ecologically sensitive development and protection of national parklands in Third World nations. The goal, says Boo, is to demonstrate the value of the parklands and wildlife preserves as important tourist attractions that can generate substantial revenue. Because of a long pattern of underfunding, these parklands often have been endangered targets of poaching, illegal mining and slash and burn clearing of vegetation for new farm land.

Boo sees the parks as drawing both committed ecotourists, who might spend their entire stay exploring them, and the beach-bound vacationer who might be lured away from the surf and sun for a day's outing. In either case, park admission fees, guides, crafts shops and food and drink concessions could help generate income for the parks and their neighboring communities, lessening the threat of illegal activities. One cautionary note is that parklands should not become so overdeveloped that the problem becomes too many visitors.

Another important characteristic of ecotourism is education. Transporting travelers to the wilds of the world is an excellent way of alerting them to the problems of preservation and perhaps enlisting their financial help. Wildland Journeys gives every tour participant a year's membership in a conservation organization in the host country. The hope, says Kutay, is that they will remain enrolled as dues-paying members in succeeding years.

"The experience of an ecotraveler is much different from a conventional traveler," says Kutay. From his point of view as a conservationist and tour operator, "It's a chance to enlighten them and inspire them to help preserve the international environment."

How do you choose an ecologically sound tour? You should question a tour company thoroughly. A good tour operator or tour sponsor should:

Make a contribution to the park or area visited. It could be in the form of donations, gifts of materials or labor. Unfortunately, "relatively few tour operators have made significant contributions to conservation of the natural areas to which they offer tours," Boo's report concluded, despite the fact they have a vested interest in the preservation of the parklands.

Send sufficient background information before the tour's departure. "You have to provide people with lots of pre-tour information to explain what they will be seeing," says Piotr Kostrzewski, who heads Cross Cultural Adventures of Arlington. His firm specializes in visits to remote peoples of the world -- a logical extension of nature touring to the cultural realm.

Provide a trained naturalist or other qualified expert to accompany the tour. Much of the value of the trip is in getting accurate and current information.

Attempt to use local products and guide services, when possible. The idea, says Boo, is to pump money into the local economy as an incentive for the local people to protect parklands. This means hiring guides from the community rather than bringing them from outside the country or even from the country's capital city. Lodgings might be arranged in locally owned guest houses rather than the big international hotel down the road.

Invite tourists from the country visited to join as tour participants. Admittedly, this is an ideal, says Boo, and not much practiced. The World Wildlife Fund believes it is as important to educate the local people as it is visitors from the United States, Europe and Japan. She would like to see tour operators subsidize perhaps one or two locals on each tour. An added advantage is that this could provide a cross-cultural experience -- a rare chance to meet local people -- for the foreign visitors.

Restrict the size of the tour group. In the early 1900s, the Sierra Club took as many as 220 people per trip into the mountain wilderness of the American West, says Charles Hardy of the organization's Outing Department. More cognizant now of the devastating impact of such a crowd, the Sierra Club generally limits its annual series of backpacking and other wilderness excursions to no more than 12 participants.

Adequately instruct participants on inoffensive or low-impact behavior. For example, shorts should not be worn in remote areas of Third World nations, particularly in Moslem countries, says Kostrzewski. Outside the big cities, "it is considered ludicrous or rude." Richard Moore says he has had to ask individuals on the Canadian seal-watching tours to remove T-shirts reading "Save the seals and kill the hunters." At the trailhead, Sierra Club hikers regularly are advised to "take only pictures and leave only footprints."

Demonstrate ethical principles of conservation. For a big tip or bribe, tour guides in East Africa have been known to drive off the road in hot pursuit of fleeing animals so photographers can get a better picture. This disturbs the animals, damages plant life and can cause erosion, says Boo. She is interested in receiving anecdotal material on unsound environmental practices witnessed by tour participants.

Among the tour operators, cruise lines and other organizations with a reputation for offering or sponsoring quality nature trips:

World Wildlife Fund: The organization sponsors a variety of wildlife protection projects throughout the world, and its annual tours usually include a visit with the field staff at one or more of them. On Dominica, site of one of the tours, efforts are being made to protect the island's virgin rain forest, the largest expanse in the Caribbean.

A one-week visit to Dominica, departing Feb. 23, features a series of guided walks in the rain forest, where a naturalist will provide commentary on tropical ecology. Participants will be on the lookout for the endangered sisserou, or imperial parrot, the largest in the Caribbean and found only on Dominica. The itinerary also will include a visit to the Carib Indian Reserve, last home of the Carib Indians after whom the Caribbean is named.

The cost of the tour from Antigua is $1,720 per person (double occupancy), which includes seven nights' lodging in small hotels and all meals. Air fare to Antigua is additional.

For information: World Wildlife Fund, Travel Program, 1250 24th St. NW, Washington, D.C. 20037, 202-778-9683.

International Fund for Animal Welfare: Every winter, some 250,000 harp seals make their way into Canada's Gulf of St. Lawrence where their pups are born on floating ice fields near the Magdalen Islands. Visitors stay in villages on the islands and make seal-watching excursions by helicopter. It's not unusual to be able to cuddle one of the wide-eyed pups.

While not on the ice fields, participants can tour the French-speaking islands, cross-country ski, snowshoe and watch the Northern Lights. Wildlife lectures and photography workshops are offered. Tours range from four to seven nights. They are scheduled for Feb. 26 to March 5, Feb. 28 to March 5, March 2 to 9, March 4 to 9, March 8 to 12, March 11 to 16 and March 15 to 20. The price from Halifax, Nova Scotia, for the four-night tour begins at $1,295 per person (double), which includes hotel lodging, some meals and at least one flight to the seals. Air fare to Halifax is additional.

For information: Natural Habitat Wildlife Adventures, One Sussex Station, Sussex, N.J. 07461, 800-543-8917 and 201-702-1525.

Sierra Club: Though noted primarily for its backpacking trips in the West, the Sierra Club also puts together an annual roster of international trips. A new one for 1991 is a 17-day cultural and ecological tour of the Soviet Union, including visits to Leningrad, Moscow, Byelorussia and the Ukraine. Cultural sightseeing will be balanced with hiking in the Carpathian Mountains, touring a nature reserve in Byelorussia with a Soviet ecological group and visiting proposed sites for new national parks.

The tour departs May 12. The price from Leningrad is $2,980 per person (double), which includes lodging and all meals. Air fare to the Soviet Union is additional.

For information: Sierra Club, Outings Department, 730 Polk St., San Francisco, Calif. 94109, 415-776-2211.

Wildland Journeys: Founded 10 years ago, Wildland Journeys specializes in nature travel to Latin America. A popular destination is the Central American republic of Costa Rica, where two 12-day camping safaris are scheduled, departing Feb. 10 and March 10.

The treks will take participants from the tropical forests of the northwest across the central mountain range to the extreme southeast corner of the country on the Caribbean. Eight nights will be spent in tents, broken by two nights in lodges along the way. The land cost is $1,545 per person, which includes most meals. Air fare to Costa Rica is additional.

Among the firm's other programs are foot safaris in East Africa and volunteer maintenance work on the Inca Trail in Peru. This year, Wildland Journeys plans to build latrines along the trail.

For information: Wildland Journeys, 3516 N.E. 155th St., Seattle, Wash. 98155, 800-345-4453 and 206-365-0686.

Journeys International: An affiliate of Wildland Journeys, Journeys International focuses its attention on Asia and Africa. One of its many programs is an annual 20-day tree-planting trek in Nepal, where the forests have been cut for firewood. Participants assist local people in what is designed to be a cultural-awareness experience.

This year's trek departs April 11. The land price is $1,495 per person, which includes lodging and most meals. Air fare to Nepal is additional.

For information: Journeys International, 4011 Jackson Rd., Ann Arbor, Mich. 48103, 800-255-8735 and 313-665-4407.

International Expeditions: One of the largest of the ecotour operators -- it offers trips to 30 destinations to about 4,000 travelers annually -- International Expeditions has organized what is being called the "1st International Rain Forest Workshop." It is to be held March 9 to 16 in the Upper Amazon River basin in eastern Peru. Although featuring noted ecological experts, the workshop has been designed primarily for tourists with an interest in learning about the rain forest and its inhabitants.

Panel topics include Amazon birds, tropical mammals, tropical forest Indians, Amazon fish, Amazon orchids, social insects, rain forest frogs, tropical butterflies, the relationship of man and the rain forest and Amazonian geography and history. Attending will be representatives from the Smithsonian Institution, the U.S. Fish and Wildlife Service, the World Wildlife Fund, the Nature Conservancy, numerous U.S. and South American universities and several natural history museums in Peru and elsewhere.

Headquarters for the event will be Explorama Lodge and Explornapo Camp, two ecologically sensitive resort facilities about 50 miles downstream from Iquitos in dense primary forest. (The facilities also are utilized for the firm's eight-day tours to the Amazon, offered year-round.) The all-inclusive cost to attend the workshop is $1,298 per person (double). Air fare to Miami is additional.

For information: International Expeditions, 1 Environs Park, Helena, Ala. 35080, 800-633-4734 and 205-428-1700.

Cross Cultural Adventures: Founder Piotr Kostrzewski's interests lie in cultural interaction. He organizes tours to remote regions where villagers rarely see outsiders, among them the mountains and deserts of Morocco and the government-restricted areas of Bastar and Nagaland in India. Following ecological principles, the tours are designed for minimal impact on the local population.

However, Kostrzewski realizes, he says, that "the fact that we are there is a bit of an intrusion." But he arranges for participants to talk with villagers and share a cup of tea or other drink with them as a way of fostering mutual appreciation. He believes this is less disturbing to a culture than "a large group of tourists driving by in a bus and stopping to take pictures. Both sides remain an enigma."

On Feb. 26, he is leading a two-week tour into an area of the Middle Atlas Mountains of Morocco. Through his personal contacts in Morocco, the group has been invited to a local feast and festival featuring colorful displays of desert horsemanship. The land cost is $2,585 per person. Air fare to Morocco is additional.

Tours to Bastar in India, one of the most undeveloped and restricted regions of the country, are tentatively planned for Feb. 1 and again in November. Bastar is home to some 62 aboriginal tribes who reportedly live without machinery or other modern devices much as their ancestors did. Located in eastern India south of Calcutta, Bastar is an area of rugged hills and lush forests. India has limited access to outsiders to preserve the primitive culture.

For information: Cross Cultural Adventures, P.O. Box 3285, Arlington, Va. 22203, 703-204-2717.

National Audubon Society: Don't think just bird-watching here. This long-established organization sponsors a variety of wildlife-viewing tours -- birds, of course, but plenty of mammals, too.

The society has chartered a 70-passenger vessel of Special Expeditions, an ecology-minded cruise line, to explore the remote bays and fiords of southeastern Alaska. The 10-day cruise departs June 26 from Prince Rupert in British Columbia. Depending on cabin, the cost ranges from $2,850 to $3,930 per person (double). Air fare is additional.

For information: National Audubon Society, 950 Third Ave., New York, N.Y. 10022, 212-546-9140.

Wildlife Conservation International: Since 1964, Wildlife Conservation International, a division of the New York Zoological Society, has been studying wildlife in Argentina's wild and windy Patagonia region. On Jan. 28, it will take a group of 15 tourists to the Punta Tombo Reserve and Research Station in Chubut Province south of Buenos Aires to help count, band and weigh the Punta Tomba colony of penguins. "Most of your time," says the organization, "will be spent in the company of hundreds of thousands of Magellanic penguins."

The two-week trip includes a day stopover to tour Buenos Aires, two nights at the Andes Mountains resort village of Bariloche and nine nights in a tent encampment at the research station. February is midsummer in Argentina, when days are long and temperatures moderate. The cost is $3,285 per person (double), which includes air fare from New York, lodging and most meals.

For information: Lynn Seno Smith, Members Afield International/New York Zoological Society, 217 East 85th St., Suite 200, New York, N.Y. 10028, 212-879-2588.